MAP20: Unholy Cathedral (Console Doom)

MAP20: Unholy Cathedral is the twentieth level of most console versions of Doom, based on the original E3M5: Unholy Cathedral with modifications made to adapt to the consoles' memory and ROM size limitations. It was converted by American McGee and originally designed by Sandy Petersen. The map first appeared on the Atari Jaguar, and was later ported to the 3DO, Game Boy Advance, Sony PlayStation, and Sega Saturn consoles.

Essentials
At the start, you can see two openings with green torches in them. Take the opening on the left, and open the door. Go through and turn left, following the passage to two skin doors. Open the north door and step through the teleporter. You will be sent to the middle of the central courtyard, surrounded by four structures; the west structure will open to reveal an enemy guarding some pickups (this structure is secret #8). From this point, step on the teleporter in the north-west corner of the courtyard.

You will arrive in a square room containing a number of demons; kill them and use the berserk pack and medikits to heal any damage. The corner of the room has two skin doors; go through the door on the right (west) and follow the hallway behind it to a marble and metal pillar. Walk through the opening in the pillar and the silver wall in front of it will open; go through this opening to a large red room containing lost souls, plus two spectres on Ultra Violence. There are switches in three corners of the room; press the north-east switch and a nearby platform will lower holding the blue skull key. There is a teleporter in the south-west corner of the room; step through it to return to the central courtyard.

You will return to the square room with the demons. Take the left (south) door this time, which leads to a hallway containing lost souls, joined by imps on Hurt Me Plenty and Ultra Violence. Follow the hallway to the blue door, open it, turn left and head through the exit door. Step on the teleport pad behind this door to finish the level.

Other points of interest
After going through the blue door, you can go straight ahead to a wooden door. Go through it to an apparently empty room; as you enter, a section of ceiling will lower behind you to seal you in, and the doors in front of you will open to reveal a number of monsters. After killing them, press the skull switch on the east wall to open an alcove containing a BFG9000 and other pickups. There is another switch in this alcove; press it so you can leave the room.

Secrets

 * 1) In the starting area, take the door on the very left flanked by short red torches. Open the wall on the left in the following room. Inside, you can get four health bonuses and a light amplification visor at the end of the room. (sector 220) The room also contains a lost soul on all skill levels, plus a demon on Hurt Me Plenty and Ultra Violence.
 * 2) On the west side of the map is a wide corridor lined with a series of red brick columns. There is a door on the west wall; opening it reveals a small room with a box of rockets and four medikits. Open the door behind these to find a seven-pointed room holding a soulsphere, a plasma gun, an energy cell pack and another medikit. (sector 75) The room also contains a number of nightmare spectres.
 * 3) In the north-west of the level is a room full of damaging nukage. On the east wall is a pair of silver symbols. Open the section of wall between them to get a radiation shielding suit (sector 54) The item is protected by an imp on Ultra Violence.
 * 4) From secret #3, step on the teleporter at the north end of the room. You will be sent to the middle of the central courtyard. The southern of the four structures surrounding this point will open, and inside is a yellow skull key. (sector 152) The item is guarded by one to three cacodemons depending on skill level.
 * 5) At the east end of the central courtyard is a glowing red square high on the wall. The wall just to the south of this square hides an alcove with a chainsaw and a soulsphere, (sector 164) but it cannot be opened due to having an incorrect linedef type (see Bugs).
 * 6) From the room you arrive in after leaving the courtyard, go through either door, then the door next to it on the other side. Step into the teleporter behind these doors and you will return to the middle of the courtyard again. The structure north of you will open; inside are two medikits and a box of bullets. (sector 123) The alcove also contains a demon on I am a Wimp or Not Too Rough, a cacodemon on Hurt Me Plenty, or a baron of Hell on Ultra Violence.
 * 7) Go through the teleporter in the south-eastern corner of the courtyard from one of the doors inside the building (i.e. not from the courtyard itself). Like secrets #4 and #6, the structure east of the central teleport will open up; its inside counts as a secret and contains a box of bullets and 14 health bonuses. (sector 121) The alcove also contains the same monster as secret #6.
 * 8) Same as secret #7, but use the south-western teleporter to access the central courtyard. Again, you must enter from inside the building rather than the courtyard. The western structure will open, revealing a box of bullets, a box of shells and an invulnerability pickup. (sector 74) The structure also holds the same monster as secrets #6 and #7.

Bugs

 * Six "hanging leg" decorations (things 216 through 221) have no flags set for any of the difficulty classes, so they do not actually appear in the level. Two hanging legs in the central area (things 220 and 221) are placed on top of one another. These issues are inherited from the PC version.
 * Pressing use on either of the south jambs of the door east of the north-east teleporter in the central area will crash the game.
 * The wall of the door to secret #5, the alcove in the east wall of the central courtyard, incorrectly uses linedef type 105, which opens a door when the tagged line is walked over. This makes the secret unreachable as players cannot walk through the wall. (The line is also set to affect sectors with tag zero, so if a player could activate the line it would cause most ceilings in the level to shut like doors, making the level unplayable.)
 * As a side-effect of the above bug, the yellow skull key in secret #4 is useless as it is not used to open any other doors.

Comparison of versions
Numerous changes exist in the level as compared to its PC version:

Removed areas

 * A secret area connecting the north hallway with the red north-western room was removed.

Room design

 * All switches use a skull switch on metal wall texture.
 * The "entrance door" is removed from the starting area.
 * The blood pool in secret #1 is changed to lava.
 * The red symbols in the hallway north of the starting area have sectors behind them on PC. These sectors are removed from console ports.
 * The pillars in the hallway west of the central area are square rather than octagonal. The sectors behind the face walls in this area are removed, and the faces are replaced with scrolling skull textures.
 * The entrance to the north-western room uses four sectors instead of eight. The floor is changed to nukage to indicate it is dangerous.
 * The walls surrounding the teleport landing pad in the middle of the central courtyard were removed.
 * The crushers protecting the switches in the blue key room were removed. The rocket launcher alcove on the east side of this room is not flagged as a secret.
 * Walking into the large room past the exit door will cause two chambers to open and release a number of monsters; on the PC version of the level, the monsters teleport in instead. The chambers contain a number of health and armor bonuses.

PlayStation
Some additional changes were made in the PlayStation port:
 * A nightmare spectre is added by the southern pillar in the west hallway on Ultra Violence.
 * Two nightmare spectres are added by the entrance to the north-western nukage room on Ultra Violence. Only one appears on Hurt Me Plenty.
 * The demons in secret #2 are replaced with nightmare spectres.

Music
The map uses the following music tracks:

Player spawns
This level contains five spawn points:
 * 1) facing north. (thing 278)
 * 2) facing south. (thing 279)
 * 3) facing south. (thing 280)
 * 4) facing north. (thing 281)
 * 5) facing north. (thing 282)

Things
This level contains the following numbers of things per skill level: